Recent advances in electric vehicle technology have resulted vehicles that have comparable performance characteristics compared to internal combustion engine vehicles. Unfortunately, one key component, the battery, remains stubbornly expensive, resulting in costly electric cars. One cannot possibly justify the price of a new electric car compared to a similarly equipment gasoline or diesel model. If, instead, one develops the lightest possible vehicle, the electric equation just might make sense.
The lightest practical vehicle is either a motocross bike, a street legal equivalent, the enduro, or it's fully street focused version, the supermoto. Such bikes often weigh a little over 100 kg. By minimizing weight, the battery requirements are minimized, and, consequently, the price as well.
Several companies have seen the light and jumped into the fray. Unfortunately, their efforts have come up short. Many save the expense of designing a new chassis from scratch, and, instead, shoehorn an electric motor and battery pack in a frame that was originally designed for and internal combustion engine. The results have been mediocre, underpowered bikes with limited range and questionable handling.
The published US patent application 2011/0036657 A1 by Bland et al. (subsequently referred to as Bland) assigned to Brammo Inc. discloses a straight electric motorcycle chassis that comprises two sides that enclose the headstock and allow attachment of batteries from above and below. Bland places the motor at the axis of the drive sprocket, with no transmission, subsequently requiring a big, heavy electric motor to generate enough torque. The motor is also fully stressed, resulting in high maintenance costs related to motor repair or replacement. In addition, the batteries are insufficient for a reasonable top speed and range.
Zero Motorcycles, from Scotts Valley, Calif., manufactures an electric motorcycle frame using a combination of tubular and hydroformed aluminum pieces that are welded together. The myriad disadvantages of welded aluminum frames are discussed in the description, below. Like the teachings of Bland, the Zero batteries are insufficient for a reasonable top speed and range.
KTM of Austria and Quantya of Switzerland both employ welded bent steel tube perimeter frames, which can be heavy.
All of the electric motorcycle manufacturers discussed above use air cooled electric motors. Compared to liquid cooled electric motors, air cooled electric motors have lower peak power outputs and vastly lower continuous power outputs.
Given growing consumer demand for high performance, low cost electric vehicles, there is a need for a new electric motorcycle developed around a new type of chassis.